1. Field of the Invention
The present invention relates to a lamp, and more particularly to a lamp that radiates high-temperature thermal energy.
2. Discussion of the Related Art
Generally, a lamp radiates light using a heated filament. Further, if the filament is heated at a high temperature, the lamp is capable of heating, drying, melting and hardening a prescribed object using the radiated heat and light from the lamp.
Such a lamp includes of a hermetic tube and a filament provided within the tube. The filament is for radiating light and high-temperature heat. In addition, the tube can be charged with an inert gas or can be set in a vacuum state. The inert gas or the vacuum state minimizes the evaporation of the filament due to the emission of electrons. Further, the tube is made of quartz glass that can withstand a high temperature.
In addition, the quartz glass is thermally treated to withstand a temperature of about 1,270K. The filament is also wound into a spiral shape in a length direction of the tube to provide a wide radiation area for effectively radiating high temperature heat.
However, the above-explained related art lamp has the following problems.
The spirally-wound filament tends to sag due to its own weight and thus contacts an inside of the tube. Therefore, because the spirally-wound filament contacts the hermetic tube, the filament is not allowed to radiate heat exceeding a temperature (about 1,270K) that would melt or transform the quartz glass tube. For this reason, the thermal energy radiation of the lamp is lowered. Specifically, according to the Stefan-Boltzmann Law of E∞T4 (E: radiant energy, T: absolute temperature), if the absolute temperature drops, the thermal energy radiation is considerably lowered. Hence, the related art lamp is not suitable for a high-temperature drying or heating function.
Moreover, as the filament is brought into contact with the tube, a temperature difference between a contact portion and non-contact portion of the filament is considerably large. Therefore, the chance of the filament breaking is increased.
Further, because the filament has a spiral shape, a length of the straightened filament is at least 1.5 times greater than that of the spirally-wound filament. Hence, the larger length of the filament substantially raises the cost of the filament. Also, because the manufacturing and assembling processes of the spirally-wound filament are complicated, productivity is lowered. It is also highly probable that the tube or filament may be broken in the assembling process.